The present invention generally relates to composite articles and processes for their production. More particularly, this invention is directed to the use of composite materials in the fabrication of load-bearing rotating rings, as an example, of the type used in the fan section of a gas turbine engine.
The maturation of composite technologies has increased the opportunities for the use of composite materials in a wide variety of applications, including but not limited to aircraft engines such as the GE90® and GEnx® commercial engines manufactured by the General Electric Company. Historically, the fabrication of components from composite materials has been driven by the desire to reduce weight, though increases in metal costs have also become a driving factor for some applications.
Composite materials generally comprise a fibrous reinforcement material embedded in a matrix material, such as a polymer or ceramic material. The reinforcement material serves as the load-bearing constituent of the composite material, while the matrix material protects the reinforcement material, maintains the orientation of its fibers and serves to dissipate loads to the reinforcement material. Polymer matrix composite (PMC) materials are typically fabricated by impregnating a fabric with a resin, followed by curing. Prior to impregnation, the fabric may be referred to as a “dry” fabric and typically comprises a stack of two or more fiber layers (plies). The fiber layers may be formed of a variety of materials, nonlimiting examples of which include carbon (e.g., graphite), glass (e.g., fiberglass), polymer (e.g., Kevlar®), and ceramic (e.g., Nextel®) fibers. Suitable thicknesses for the individual fiber layers and the resulting PMC material depend on the particular application of the composite structure being produced. Whether a PMC material is suitable for a given application depends on the structural requirements of the application as well as the feasibility of fabricating a PMC article having the required geometry.